APT

1. SRI KRISHNA COLLEGE OF ENGINEERING AND TECHNOLOGY
DEPARTMENT OF MECHATRONICS ENGINEERING
MODULE 1
Session: Automated Part Programming
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2. SESSION OBJECTIVES
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 On the completion of this session, the students might
be able to understand,
▪ Automated Part Programming
▪ Programming methods

3. Topics
 Introduction
 Programming methods
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4. APT
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 APT – Automatically Programmed Tooling
 3D NC part programming developed in late 1950’s
 Important language in CAD/CAM
 Not only a language but also computer program that processes the APT
statements
 4 basic statements:
 Geometry – define the geometry elements that comprise the part
 Motion commands – specify the tool path
 Postprocessor statements – control m/c tool operation(speed, feed)
 Auxiliary – Miscellaneous statements (name, comments)

5. APT geometry statements
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 Six or fewer characters
 Characters are almost always letters of the alphabet
SYMBOL = GEOMETRY TYPE/descriptive data
Geometry element Major word
• Line
• Circle
• Point
• Plane
Minor words
• Numerical values
• Dimensions

6. Points
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P1 = POINT/20.0,40.0,60.0
P2 = POINT/INTOF,L1,L2
P3 = POINT/XSMALL,INTOF,L1,C1
P4 = POINT/YSMALL,INTOF,L1,C1
P5 = POINT/CENTER,C2
P6 = POINT/C2,ATANGL,45
P1 = (x,y,z)
C1
C2
L1
450
L2
P2
P3
P4
P5
P6

7. Lines
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L1
L2
P1
P2
L1 = LINE/P1,P2
L2 = LINE/20,30,0,70,50,0
L3 = LINE/P3,PARLEL,L1
L4 = LINE/P2,PERPTO,L1
L5 = LINE/P2,PERPTO,YAXIS
L6 = LINE/P3,LEFT,TANTO,C1
L7 = LINE/P5,ATANGL,45,L6
L4
P3
L5
P4
L3
C1
450
L6
P5
L7

8. Planes
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 Specified using three points
 Non-collinear points
 Can also be defined parallel to another plane
PL1 = PLANE/P1,P2,P3
PL2 = PLANE/P2,PARLEL,PL1
P2
P1
P3
PL1
PL2

9. Circle
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P1
R
C1 = CIRCLE/CENTER,P1,RADIUS,32
C1 = CIRCLE/CENTER,P1,P2,P3
C1 = CIRCLE/CENTER,P4,TANTO,L1
C1
L1
P1
P2
P3
P4

10. Rules
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 Co-ordinates must be specified in the order x,y,z
 Any symbols used as descriptive data must have been previously defined
 A symbol can be used to define only one geometry element
 Only one symbol can be used to define any given element
C1 = CIRCLE/CENTER,P1,P2,P3
C1 = CIRCLE/CENTER,P1,P2,P3
C1 = CIRCLE/CENTER,P4,TANTO,L1
C1 = CIRCLE/CENTER,P1,P2,P3
C2 = CIRCLE/CENTER,P1,P2,P3

11. APT Motion commands
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MOTION COMMAND/descriptive data
POINT TO POINT CONTOURING
 Only GOTO and GODLTA
 GODLTA specifies incremental
positioning
GOTO/P2
GOTO/25.0,40.0,0
GODLTA/50.0,120.0,0
GODLTA/0,0,-50.0
GOTO/P1
FROM/PTARG
Drive surface
Cutter
Check
Surface
Part Surface
Tool
 Tool’s position continuously
controlled
 Tool is directed along two
intersecting planes until it
reaches a third surface

12. Contouring commands
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Drive surface
Check
Surface
Part Surface
Cutter trajectory
TO
Drive surface
Check
Surface
Part Surface
Cutter trajectory
ON
Drive surface
Check
Surface
Part Surface
Cutter trajectory
PAST
PL1
Cutter trajectory
Check
Surface
C1
TANTO
GOUP
GOFWD
GORGT
GOLFT
GODOWN
Previous tool position

13. Example
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PTARG
(Starting location)
PL4
PL3
PL1
PL2
FROM/PTARG
GO/TO,PL1,TO,PL2,TO,PL3
GORGT/PL3,PAST,PL4
FROM/PTARG
GO/TO,L1,TO,PL2,TO,L3
GORGT/L3,PAST,L4

14. Postprocessor and Auxiliary statements
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POSTPROCESSOR COMMAND/descriptive data
UNITS/MM - Specifies unit
INTOL/0.02 – Inward tolerance
OUTTOL/0.02 – Outward tolerance
CUTTER/35.0 – Cutter diameter
SPINDL/1000,CLW – Spindle CW rotation
SPINDL/OFF – Spindle off
FEDRAT/40,IPM – Feed rate in mm/min or inches/min
RAPID – Rapid traverse

15. Postprocessor and Auxiliary statements
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PARTNO – First statement in an APT program
MACHIN/– Specifies the processor in turn the M/C tool
CLPRNT– Cutter location print
REMARK– Explanatory comments
FINI – End of an APT program

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END